Detect if page is loaded inside WKWebView in JavaScript

Question

How can I reliably detect using javascript that a page is loaded inside a WKWebView? I'd like to be able to detect these scenarios:

• iOS & WKWebView
• iOS & Safari
• not iOS

There is a similar question about UIWebView here. But it's quite old and I'm not sure if same still applies to WKWebView.

Answer 1

Update: This no longer works, see the higher-rated answers above instead!

You can check for the existence of window.webkit.messageHandlers which WKWebKit uses to receive messages from JavaScript. If it exists, you're inside a WKWebView.

That combined with a simple user agent check should do the trick:

var iOS = (navigator.userAgent.match(/(iPad|iPhone|iPod)/g) ? true : false);
var isWKWebView = false;
if (window.webkit && window.webkit.messageHandlers) {
    isWKWebView = true;
}